Richardson A K, Jacobs P
Bristol Haematology and Oncology Centre, Horfield Road, Bristol, BS2 8ED, UK.
Radiography (Lond). 2017 Nov;23(4):310-313. doi: 10.1016/j.radi.2017.07.003. Epub 2017 Aug 2.
Implementation of the Clarity Autoscan (Elekta) Transperineal Ultrasound (TPUS) system in Bristol is the first of its kind in the UK and we have already shown its utility in interfractional Image Guided Radiotherapy (IGRT). This study establishes the extent of intrafraction prostate motion as measured by Clarity and explores the potential benefits of TPUS for intrafraction monitoring.
Monitoring data was analysed for 526 fractions from 20 localised prostate cancer patients. Intrafraction prostate displacements exceeding thresholds of 3 mm, 7 mm and 10 mm along patient axes were assessed for frequency and duration of motion.
Prostate motion exceeds the above displacement thresholds during 52%, 8%, and 2% of fractions analysed. Displacement at the 3 mm threshold occurred for 100% of patients, 60% at 7 mm and 35% at 10 mm. The mean frequency and duration of displacements is low for the overall population. In contrast specific patients exhibit much higher displacement values. Posterior motion is most common, averaging at 24% of the treatment time at 3 mm, 3% at 7 mm and 1% at 10 mm, ranging up to 92%, 35% and 10% for individual patients.
Intrafraction monitoring with Clarity has the potential to improve accuracy through application of in-treatment motion correction. This is most beneficial for specific patients who exhibit a higher frequency and/or duration of prostate motion. Consideration must be given to the added time implications and radiographer workload in clinical practice to correct for prostate motion. Clarity could help facilitate future protocols using tighter treatment margins, although further research is required.
在布里斯托尔实施的Clarity Autoscan（医科达公司）经会阴超声（TPUS）系统在英国尚属首次，我们已经展示了其在分次间图像引导放射治疗（IGRT）中的效用。本研究确定了通过Clarity测量的分次内前列腺运动程度，并探讨了TPUS用于分次内监测的潜在益处。
分析了20例局限性前列腺癌患者526个分次的监测数据。评估了沿患者坐标轴超过3毫米、7毫米和10毫米阈值的分次内前列腺位移的运动频率和持续时间。
在所分析的分次中，分别有52%、8%和2%的分次前列腺运动超过上述位移阈值。3毫米阈值时的位移在所有患者中出现率为100%，7毫米时为60%，10毫米时为35%。总体人群中位移的平均频率和持续时间较低。相比之下，特定患者表现出更高的位移值。向后运动最为常见，在3毫米时平均占治疗时间的24%，7毫米时为3%，10毫米时为1%，个别患者可达92%、35%和10%。
使用Clarity进行分次内监测有可能通过应用治疗中的运动校正来提高准确性。这对那些前列腺运动频率和/或持续时间较高的特定患者最为有益。在临床实践中校正前列腺运动时，必须考虑增加的时间影响和放射技师的工作量。Clarity有助于推动未来采用更窄治疗边界的方案，不过仍需进一步研究。
